ZIRCONIA COATINGS REALIZED BY MICROWAVE PLASMA-ENHANCED CHEMICAL-VAPOR-DEPOSITION

This study presents an evaluation of a new process microwave plasma-en hanced chemical vapor deposition to deposit thermal barrier coatings ( TBCs) consisting of yttria partially stabilized zirconia. A reactor ha s been designed and realized at ONERA with a view to provide an altern ative technique to the processes already in use for depositing TBCs on gas turbine airfoils. It is demonstrated that zirconia coatings havin g a columnar structure can be deposited with a high rate (up to 5 mu m min(-1)) compatible with production requirements. Plasma study by opt ical emission spectroscopy has lead to the identification of reactive species and to the determination of the plasma distribution and locati on with respect with the gas flow and the reactor chamber geometry. A systematic study has been engaged to determine the influence of operat ing parameters on the structure, the morphology of the coatings and th e deposition rate.